This invention relates in general to imaging systems. More specifically, it relates to a laser projection system that records a visible image on a three-dimensional object.
It is known to use lasers to project and record images onto objects in applications such as semiconductor manufacture, photocopying, medical imaging, and printers. In these applications, the geometry is typically well controlled and fixed. The projected light beam does not guide the placement of a three-dimensional (“3D”) object, and the system typically has optical components that compensate for the well-defined curvature(s) of the object, e.g. a cylindrical drum. Nor is there optical feedback from the object back to the projecting laser. In most cases the laser light used for image recording is not eye safe, and the system is usually contained in an enclosure.
3D laser projection is also a known technology used in manufacturing processes as a soft tooling technique. A laser projector utilizes computer aided design (“CAD”) data for a given 3D object to produce rapidly moving, vector-scan, laser beam. Typical linear velocities of the beam spot on an object can be near 45,000 inches per second. The beam strikes a given surface of the object precisely following a predetermined, computer-controlled trajectory in a repetitive manner. There is typically optical feedback from a target object to the projector in these manufacturing applications. With sufficiently high beam speed and refresh rate, the trajectory of the projected beam on the object appears to human eye as a continuous glowing line. A set of projected lines or contours will appear as a solid glowing image on the surface of an object. The projected image is perceptible by a viewer as a glowing template that can be used to assist in the precise positioning of parts, components, work pieces, and the like on any flat or curvilinear surface in 3D space. In addition, laser projection can be used to produce a glowing image of a text, e.g. to convey part numbers, work instructions, and other alphanumeric information.
Presently 3D vector-scan laser projection technology is widely used in manufacturing of composite parts, in the aircraft and marine industries, or other large machinery assembly processes, truss building, and other applications. It gives the user ability to eliminate expensive hard tools, jigs, templates, and fixtures. It also brings flexibility and full CAD compatibility into the assembly process.
It is desirable to use templating by 3D laser projection not only for positioning in assembly and part placement, but also for alignment assistance in drilling holes, cutting edges, painting, and other material processing operations. However, in such material processing applications the laser beam would be blocked by the material processing tools, fixtures, and workers, thus preventing proper alignment of the tool with the point aimed by the laser. It would also be necessary in many cases to separate the laser projection operation from the material processing operation in space and in time.
It is therefore a principal object of this invention to provide a 3D projection system and method that can both project a light image on a surface of a 3D object and record that image so that it persists on the object in the absence of the projection.
Another object of the invention is to provide a 3D laser projection system and method that allows selective application of the image on portions of the object.
Still another object of this invention is to provide an apparatus and method to guide the placement of a layer or layers of a material on the surfaces of the 3D object, and further subsequent processing of a laser-recorded image.
A further object of this invention is to provide an apparatus and method with the foregoing advantages that is also substantially insensitive to ambient light or to a conventional glowing template for a period of time sufficient to accomplish the desired processing.
Still another object is to provide a laser projection system with the foregoing advantages capable of operating at such laser beam power levels that it does not need to be enclosed and does not require operator to use protective eyewear.
Yet another object of the invention is to provide a recorded image on a 3D object produced by laser projection that can be readily removed from the object even after exposure and fixing.
A further object of the invention is to reduce the cost and enhance flexibility of large scale, high-precision manufacturing processes.